class_docstr: To deal with ValueChoice used as a parameter of a basic unit.
  
  Should be used together with :class:`ParameterChoiceLeafMutator`.
  :class:`ParameterChoiceMutator` is an empty-shell mutator.
  It calculates all the parameter values based on previous mutations of :class:`ParameterChoiceLeafMutator`.
code: def __init__(self, nodes: List[Tuple[Node, str]]):
      super().__init__()
  
      self.nodes = nodes
  
      self._within_dry_run = False
  
imports: from __future__ import annotations
  from typing import Any, List, Tuple, Dict, Iterable, cast
  from nni.mutable import MutableExpression, Categorical, frozen_context, label_scope
  from nni.nas.space import Graph, GraphModelSpace, Node, StationaryMutator, Mutator
  from nni.nas.space.graph_op import Cell
label_desc: Use image node_id 1 to create a new ParameterChoiceMutator object from inherited base classes: StationaryMutator with example: obj = ParameterChoiceMutator(nodes)